Planning to install a ground mounted antenna like a butternut or hustler in the spring and planning to install about 40 28' radial wires.

I plan to solder the ring terminals onto the wires so I started looking for the ring terminals.  Since I'm soldering should I just use uninsulated terminals and then apply an anti-oxidant to the connection once I bolt them onto the stainless steel radial plate?

I found ring terminals that have shrink tubing but you need a special tool to crimp the connector onto the wire and I would not be able to solder the connection.

So uninsulated soldered with anti-oxidant or insulated with heat shrink?  I prefer soldered connections myself but I do want to keep water from infiltrating the insulated radial wire

It does not matter. You should use the anti oxidant between on the terminal and screws on the antenna.

I just put up a 4BTV, and used 4 conductor phone line for radials:
- measured and cut the radials to 4 lengths
- stripped the outer shield off,
- separated the radials by color
- clamped/ crimped all radials to 1 ring terminal by color (so 1 of each length in each terminal)
- slid heat shrink up to terminal, heated
- ran radials on ground
- wing nutted the terminals onto 1 bolt on the antenna mount (made sure it was electrically connected to the coax shield/ plug)
- started making contacts!

I did not worry that the radials were all insulated still (they should then be slightly shorter for resonance, but if they are not elevated it does not matter). You are trying to make a ground plane, so if water invades the insulation it should hurt nothing, since it really does not matter if they are resonant.

I also figure if it does not work I can spend another $5 on ring terminals and do it differently, so far so good (3 weeks).

Ha, my longer radials are from recycled direct burial that went to the pool I demoed.  Three  long #10 insulated wires.  IIRC they were 98 feet long.  In addition to the 32 other radials I had down.  

If I had a source of free wire, I'd make my own for sure.  

For my Butternut I used one of these ground radial kits, which has soldered/uninsulated terminals, and used Jet-Lube SS30 anti-seize on all the connections.  Working fine so far after about 1 year.  I plan on installing a second set of radials when the ground thaws.  If you wanted to go to the trouble, you could get heat-shrink tubing and cut pieces to put over your soldered connections.  That adds to the time/expense and may not be necessary.

I've got part of a roll of Cat5 cable and thought about stripping the wires out of it to use for ground radials, but it's a PITA to work with.  Might try making a trap or fan dipole with it though, just for shits & giggles.

iirc, I put flux on, inserted in ring, crimped and then flowed solder in.  Then slid up the shrink tube and sealed it.   Dipped the other end in caulk.